Dell Precision 5810 Installation -- Is EFI good?

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npaust · Post by **npaust** » Tue Aug 18, 2015 9:00 pm

The background:
My work hardware replacement cycle has come around, so I just got a shiny new Dell Precision 5810 workstation. 6 cores, 32 GB of RAM, a 200 GB boot SSD, and two 4 GB spinning disks that I'm going to put in a btrfs mirrored raid for the data.

This is about my seventh gentoo machine, but the first one with EFI. I followed the handbook exactly using efibootmgr and it didn't work... played around with the firmware and still couldn't get it to boot... tried using grub and it still didn't work... (I generally just got messages that said that "boot failed").

After my third day of banging my head against the wall, I decided to try going back to a MBR on the boot drive and using the legacy bios on the machine and I now have a working copy of gentoo.

My question though is whether there's anything I'm missing out on by not using GPT on the boot drive and the UEFI interface on the computer. Does that stuff actually matter at all after the system boots?

Logicien · Post by **Logicien** » Tue Aug 18, 2015 10:14 pm

The Gpt partitions tables allow to manage more and larger partitions and bigger hard drives too. The EFI system have some performance advantages over the Bios. This is what I ever read.

The problem is if you cannot boot in EFI mode, the Gpt table may not be usefull in Bios mode. Convert it to Dos partitions table is not what I like to do.

I just come to finish a nightmare with the Lenovo Thinkpad T420 in UEFI mode. The first thing I did was to erase Windows completely. I have been able to make Ubuntu and ArchLinux boot in this mode showing their Grub menu. The EFI entry of the distribution must be in the boot sequence of the EFI setup to be seen. I had to use efibootmgr command to see the Arch in the EFI firmware menu.

It look like if installing Grub in Efi mode do not work if the grub-install command is executed in chroot. The files are copied correctly to the EFI partition, but the EFI variables are not updated correctly. This fact make Archlinux and Debian fail to boot in EFI mode. Ubuntu installation do the job correctly. I have been able to boot in Efi mode.

The solution for me was to manipulate the EFi variables with the root user of the OS who have booted in Efi mode. This is what I did using Ubuntu Efi boot to put ArchLinux in the top of the boot sequence using efibootmgr. The Efi firmware saved the modifications and showed me the Grub Arch menu the next boot.

I try to do it in chroot, but it haven't work even if all the virtual filesystems where binded before into the sub-root directories of the chroot. I haven't seen any option about the secure boot in the Efi/Bios setup. Just the choice of UEFI only, Legacy only and Both.

Note that Ubuntu have is own signed key for Efi. When booting it told me that it was booting in insecure mode. More tests I will do using something else than Ubuntu to manipulate the Efi variables.

The Efi norme is more tricky than usefull. It give the insdustry the monopole using a security concern.

ian.au · Post by **ian.au** » Tue Aug 18, 2015 10:41 pm

My question though is whether there's anything I'm missing out on by not using GPT on the boot drive and the UEFI interface on the computer. Does that stuff actually matter at all after the system boots?

IMO, if the relatively small disk sizes you stated are correct, no. GPT is only required if you need support for partitions > 2TB. UEFI only makes sense if it works

Re UEFI install not working, the gotcha that bit me first time I tried it was trying to install efi after booting install media in legacy bios mode. In short, you need to boot in efi mode to install efi. Once I got that (after a litany of failed boots that looked a lot like what you just described) I booted sysrescuecd in efi and installed a booting system with no trouble.

To see if your bios is capable of / enabled for UEFI boot a useful trick is to boot from sysrescuecd, if the boot selection menu appears in colour, with the traditional blue background, you have booted in legacy bios mode, so you need to dive into the bios and set UEFI up there, if the background is b&w UEFI is enabled.

ShanaXXII · Post by **ShanaXXII** » Wed Aug 19, 2015 1:32 pm

You should also consider GPT/UEFI if you would like to have more than 4 primary partitions (max of MBR).
I switched over from MBR/BIOS to GPT/UEFI on my Lenovo E550.
I wiped windows and reinstalled it on gpt. I currently have7 partitions, containing Windows, Gentoo, data and some other distributions.

Yamakuzure · Post by **Yamakuzure** » Thu Aug 20, 2015 8:43 am

If you have a Dell Precision, do *not* use efibootmgr or any other software. Use the EFI Boot Manager that comes with your BIOS. I have a Dell Precision M4800 and the setup using the BIOS is working like a charm here. (IIRC the efi file is /boot/efi/EFI/gentoo/grubx64.efi)